Telephone and telegraph system



Nov. 4, 1939; L. c. ROBERTS 1,730,245

TELEPHONE AND TELEGRAPH SYSTEM Filed Sept. 27. 1929 RE, 3 v g ter 0M Frw a 1 77 L ZW INVENTOR BY Z.C]f0bers ATTORNEY Patented Nov. 4, 1930UNITED. STATES PATENT OFFICE LELAND Gl ROBERTS, TOWACO, NEW JERSEY,ASSIG-NOR T0 AMERICAN TELEPHONE TELEGRAPH COMPANY, A CORPORATION OF NEWYORK TELEPHONE AND TELEGRAPH SYSTEM Application filed September 27,1929. Serial No. 395,629.

This invention relates to telephone systems of the well known four-wiretype and more particularly to arrangements for utilizing the conductorsof such systems for telegraph'as well as telephone purposes undercertain conditions when the wires of the systems are so transposed thatthe phantom circuits will be separated from their side circuits at thetransposition points. v

The four-wire type of telephone system comprises two one-way linesections each for transmission in opposite directions. Oneway repeaterswould ordinarily be included in these one-way line sections at variouspoints. Furth'ermore, two one-way line sec 'tions each transmitting inthe same direction and being parts of different four-wire systems, mightbe arranged in quads and utilized for the production of phantomtelephone cir cuits. In certain types of systems, the oneway linesections in one quad might be connected through amplifiers at repeaterpoints to one-way line sections in the same quad. The phantom circuitsmight also be connected at repeater points to the conductors in the samequad. In other words, under such conditions, the phantom circuits wouldnot be separated from their side circuits. In systems of this type, itwould be possible to transfer a metallic telegraph circuit at an intermediate repeater point from one pair of a particular four-wirecircuit to the other pair of conductors of said four-wire circuit. Asthe phantomcircuits are not separated from the side circuits,anytelephone energy which might be transmitted over such a telegraphconnection from the phantom lineassociated therewith would'betransmitted back to the station of its own origin in the phantom linewhich was the other side of the same circuit, and might cause echo butwould not cause any cross-talk.

However, it is oftenfound desirable to transpose the conductors of thevarious quads in a system at certain points so that the conductors inone quadwill be separated from each other and willbe extended as partsof other quads. Sucha transpositionarrangement might readily resultinthe phantom circuits being separated from their side circuits in onequad and result in their being com pleted over the conductors of anotherquad. If'under such conditions, a metallic telegraph circuit wasconnected at an intermediate re peater point from one pair of afour-wire circuit to the other pair of said circuit, any telephoneenergy which might be transmitted over such a telegraph connectionfromthe phantom line associated with one end thereof, would not betransmitted back to the station of its own origin so as to causeharmless echo, but would be transmitted over a new phantom line to a newstation and would cause undesirable phantom cross-talk. The phantomcircuit would be made noisy, also, if the telegraph circuits or thepairs comprising it were transferred to two different cables.

The primary purpose of the arrangements of the lnvention 1s to providearrangements whereby. undesirable phantom cross-talk and noise maybeprevented from occurring due to the telegraph connections in the abovetype of systems. Accordingly, there will be provided in the telegraphconnection, a phantom by-pass coil. This coil is connected in thetelegraph circuit with its windings series opposed for the side circuitand, therefore, in

parallel aiding for the phantom. Its impedance to the telegraph current,therefore, is non-inductive reslstance, which maybe made 'small'enoughso that itwill not degrade transmission seriously; To the phantom,however,

the coil is inductive, and, therefore, prevents crosstalk from onephantom circuit to the other. In other words, the phantom by-pass coilwill effectively open the telegraph circuit for currents transmittedover the sides thereof in parallel and prevent their transmission butwill readily transmit the currents transmitted .over the sides thereofin series. Other objects and features of the invention will appear morefully from the detailed description thereof hereinafter given. H Theinventionmay be more fully understood from the following descriptiontogether with the accompanying drawing in the figure of which is shown acircuit diagram embodying a preferred form of the invention.

In the drawing are shown two line sections L WE and L W]':] in the quadA. and'adapted for transmission from IV to E. Line section L VVE is oneside of a four-Wire circuit. The other side of this four-wire circuit isthe line section L EVV in quad E. Line section L E may be one side of afour-Wire circuit. The other side may be line L EI/V in quad F. Linesection LJVE may be extended at the repeater station through therepeater R to the line section L in quad B. Line section LJVE maybeextended at the repeater star' tion throughthe repeater R to linesection.

L in quad D. In other words, the two line sections in quad A may beseparated and connected to conductors in other quads. This transposingof the conductors is desirable to minimize cross-talk between thevarious circuits in that it limits the distance for which twocircuitsare exposed to each, other in the same quad. The line sectionsin quad A are phantomed to produce the phantom circuit LF Obviously whenthe lines are transposed the phantom circuit will be separated from itsside circuits. The phantom circuit LF is shown connected to repeater RFand then by a phantom connection to circuits L and L in quad C. In asimilar manner, the other line sections of the various quads might be sotransposed that the phantom circuits would be separated from the sidecircuits .and the circuits in each quad might be separated from eachother. I

' In order that the various lines may be utilized for telegraphpurposes, means are provided for transmitting the telegraph currentsbetween the various lines at repeater points. These means comprisemetallic telegraph connections from one side of a four-wire circuit tothe other side of such four-wire circuit. For example, the telegraphcircuit 13 will be provided and will be connected by the composite set12 to line LJVE- and Will be con nected by the composite set 1 1 to lineL EW.

These connections may be established at points of approximately the sametransmission level such as at the inputs of the repeaters connected toeach of said lines. In a similar manner, the telegraph conductor 16 willbe provided and Will beconnected by composite set to. line L WE and willbe connected by composite set 17 to line L EN. Other telegraph legsmight be provided between the sides of other four-wire circuits in thesystem. These, however, have been omitted for the sake of simplicity inthe drawing.

In a system of the above type in which the transposition of the linescaused the phantom circuits. to be separated from their side circuitssuch telegraph connectionsmight cause phantom crosstalk and noise. or inother words, might cause disturbances to exist on the various phantomlines. For example, a

portion of the telephone energy, which was transmitted oyer phantom lineLF or in other wordsover the sides of lines L WE and in parallel,mightbe transmitted over .telephoneenergy from phantom line .LF

mightbe transmit-ted over telegraph circuit 16 and cause crosstalk onphantom l1ne LF In accordance with the arrangements of this invention,phantom by-pass coils will be provided in each telegraph leg. The coils18 and 19 have been shown included in the telegraph legs 13 and 16,respectively. As has been pointed out, the windings of these coils willbe so arranged to be series opposed for the side circuit and thereforein parallel aiding for the phantom. In other words, currents transmittedover the sides of circuit LIVE in series, and hence transmitted over thecoiuluctors of circuit 13 in series would be readily transmitted throughcoil 18. IIowever, when lines LIVE and LJIVE are used as sides of aphantom line the currents will be transmitted in parallel over theconductors of each of said circuits. Such currents would be transmittedin parallel over the sides of circuit 18 and their transmission would beeffectively opposed by the coil 18. Hence, the currents intended for thephantom line LF will not cause any cross-talk or noise on the phantomlines LF and LF lVhile the invention has been disclosed as embodied incertain specific arrangements which are deemed desirable, it isunderstood that it is capable of embodiment in many other and widelyvaried forms without departing from the spirit of the inventions asdefined by the appended claims.

What is claimed is:

l. A transmission system comprising a plurality of foi1rwire telephonecircuits having their one-way circuits arranged in quads and arrangedfor the production of phantom circuits, the individual circuits being sotransposed at a point that the phantom circuits will be separated fromtheir side circuits, telegraph circuits Connected between the one-waycircuits of certain of said fourwire circuits, and means in saidtelegraph circuits I for preventing the transmission thereover ofcurrents from said phantom c cuits- 2. A transmission system comprisinga plurality of four-wire telephone circuits having their one-waycircuits arranged in quads and arranged for the production of phantomcircuits, the individual circuits being so transposed at a point thatthe phantom circuits will be separated from their side circuits,telegraph'circuitsconnected between the on way i cuits of, c rtain o sid. f u -wi Vcuits at points'of about the same transmission level, andcoils in said telegraph circuits having their windings series opposedand parallel aiding.

3. A transmission system comprising a plurality of four-wire telephonecircuits having their oneway circuits arranged in quads and arranged forthe production of phantom circuits, the individual circuits being sotransposed at a point that the phantom circuits will be separated fromtheir side circuits, telegraph circuits connected between the one-Waycircuits of certain of said fourwire circuits at points of about thesame transmission level, and means in said telegraph circuits forpreventing the transmis sion thereover of currents applied to the sidesof said circuits in parallel.

4. A transmission system comprising a plurality of four-wire telephonecircuits having their one-Way circuits arranged in quads and arrangedfor the production ofphantom circuits, the individual circuits being sotransposed at a point that the phantom circuits will be separated fromtheir side circuits, telegraph circuits connected between the one-waycircuits of certain of said fourwire circuits at points of about thesame transmission level, and means in said telegraph circuits forpreventing the transmission thereover of currents applied to the sidesof said circuits in parallel but readily allowing the transmissionthereover of currents applied to the sides of said circuits serially. V

In testimony Wheref,,I have signed my name to this specification this thday of September, 1929.

LELAND G. ROBERTS.

